"Living in the same building means you tend to share the same socioeconomic background and interests, and giving people information on things like where to eat and where to shop makes it very, very relevant."

For the moment, the LifeAt.com services are only available in the US. Each building website costs about $6,000 to set up. By the end of the year more than 1,000 buildings will have set up their own localised social networking websites.